On 4/30/20 12:06 PM, Numan Siddique wrote: > On Thu, Apr 30, 2020 at 1:41 PM Numan Siddique <num...@ovn.org> wrote: > >> >> >> On Thu, Apr 30, 2020 at 8:43 AM Han Zhou <hz...@ovn.org> wrote: >> >>> On Wed, Apr 29, 2020 at 4:50 PM Han Zhou <hz...@ovn.org> wrote: >>>> >>>> >>>> >>>> On Wed, Apr 29, 2020 at 2:45 PM Dumitru Ceara <dce...@redhat.com> >>> wrote: >>>>> >>>>> On 4/29/20 9:57 PM, Han Zhou wrote: >>>>>> >>>>>> >>>>>> On Wed, Apr 29, 2020 at 12:17 PM Numan Siddique <num...@ovn.org >>>>>> <mailto:num...@ovn.org>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Wed, Apr 29, 2020 at 9:57 PM Dumitru Ceara <dce...@redhat.com >>>>>> <mailto:dce...@redhat.com>> wrote: >>>>>>>> >>>>>>>> In some cases, if the NB/SB databases ovn-northd connects to are >>>>>>>> inconsistent, ovn-northd might generate transactions that fail >>>>>>>> continuously due to failed integrity checks on the SB database >>> server. >>>>>>>> >>>>>>>> The first patch of the series addresses inconsistencies due to >>> stale >>>>>>>> Datapath_Binding records in the SB database. >>>>>>>> >>>>>>>> The second patch of the series addresses inconsistencies due to >>> stale >>>>>>>> tunnel_key values in various SB database table records. >>>>>>>> >>>>>>>> Reported-by: Dan Williams <d...@redhat.com <mailto: >>> d...@redhat.com>> >>>>>>>> Reported-at: https://bugzilla.redhat.com/1828637 >>>>>>>> Signed-off-by: Dumitru Ceara <dce...@redhat.com >>>>>> <mailto:dce...@redhat.com>> >>>>>>>> >>>>>>>> Dumitru Ceara (2): >>>>>>>> ovn-northd: Clear SB records depending on stale datapaths. >>>>>>>> ovn-northd: Fix tunnel_key allocation for SB records. >>>>>>> >>>>>>> >>>>>>> Hi Dumitru, >>>>>>> >>>>>>> I did some testing in my ovn-fake-multinode setup. These are my >>>>>> observations. >>>>>>> >>>>>>> I created a logical switch sw0 with 4 logical ports. So the next >>>>>> tunnel key should be 5. >>>>>>> I stopped ovn-northd and created a couple of port_binding entries >>>>>> manually using >>>>>>> "ovn-sbctl create port_binding" with tunnel keys 5 and 6. >>>>>>> I also created a logical port in sw0. Then I started ovn-northd. >>>>>> ovn-northd deletes the port binding >>>>>>> entries added by me and creates the port_binding entry for the >>> logical >>>>>> port with the tunnel_key=5 >>>>>>> in the same transaction. >>>>>>> >>>>>>> I think ovn-northd syncs the south db based on the contents of the >>>>>> north db. >>>>>>> >>>>>>> There's no harm in having your patches. But I'm not really sure if >>> it >>>>>> resolves the issue we have observed. >>>>>>> >>>>>>> Just to brief everyone about the issue we are seeing, we see below >>>>>> logs in ovn-northd. >>>>>>> >>>>>>> ******* >>>>>>> 2020-04-16T23:02:33Z|00127|ovsdb_idl|WARN|transaction error: >>>>>> {"details":"Transaction causes multiple rows in \"Port_Binding\" >>> table >>>>>> to have identical values (23eb9016-45f9-4158-be35-77b2713b9a0f and >>> 7) >>>>>> for index on columns \"datapath\" and \"tunnel_key\". First row, >>> with >>>>>> UUID e4f11a7b-09b6-454f-a125-34cc4b144ef6, had the following index >>>>>> values before the transaction: bdbb436e-f98c-4651-9b80-6e8b95044560 >>> and >>>>>> 7. Second row, with UUID d37cc3f1-8633-440f-b145-8222a0d4723c, >>> existed >>>>>> in the database before this transaction and was not modified by the >>>>>> transaction.","error":"constraint violation"} >>>>>>> ****** >>>>>>> >>>>>>> And because of this constraint violation error, ovn-northd cannot >>>>>> further write to the sb db until it is restarted. >>>>>>> >>>>>>> In my opinion this can only happen if ovn-northd doesn't see the >>> port >>>>>> binding row (which is actually present in the DB) in its IDL >>> in-memory db. >>>>>>> I suspect this could have happened when ovn-northd reconnects to >>> the >>>>>> same master or connects to the new master and it doesn't get the >>> proper >>>>>>> updates. >>>>>>> >>>>>>> Maybe in this case, the IDL should request the db contents with txn >>> id >>>>>> =0, so that it receives the complete dump of the db. >>>>>>> >>>>>>> Is it possible that ovn-northd sees a port binding with a tunnel >>> key >>>>>> 'x' and still allocates the same tunnel id 'x' to a new logical >>> port ? >>>>>>> If so, then definitely your patches makes sense. >>>>>>> >>>>>>> @Han - Have you seen this issue in your deployments ? Do you have >>>>>> comments here ? >>>>>>> >>>>>>> Thanks >>>>>>> Numan >>>>>>> >>>>>> I never saw such issue before, but I am not sure if this is possible >>> due >>>>>> to bugs. Currently there is a bug fix under review: >>>>>> >>> >>> https://patchwork.ozlabs.org/project/openvswitch/patch/20200422183842.6303.99600.st...@dceara.remote.csb/ >>> . >>>>>> However, northd doesn't conditionally monitor the rows so I am not >>> sure >>>>>> if this is the root cause of the northd inconsistency issue >>> discussed >>> here. >>>>>> >>>>>> I don't think we should fix in northd (or ovn-controller) to handle >>> the >>>>>> inconsistency of ovsdb. The consistency should be expected from >>> ovsdb >>>>>> and we should fix ovsdb/IDL when there is such kind of bug. >>> Otherwise, >>>>>> there might be too many places to fix and even re-design. My >>>>>> understanding is, if the ovsdb IDL sees a temporarily stale data, >>> the >>>>>> current northd/ovn-controller logic should be able to correct >>> themselves >>>>>> once the data is up-to-date. Moreover, for northd, it is connected >>> to >>>>>> leader-only in clustered mode, which avoids the possibility of >>> seeing >>>>>> staled data in northd (unless there is a bug). >>>>>> >>>>>> To summarize, I think we need to find the root cause of the >>>>>> inconsistency between IDL and server and fix it there, instead of >>>>>> changing ovn-northd to accommodate the inconsistency. (consistency >>> is >>>>>> the biggest advantage of OVSDB, to ease the application >>> implementation). >>>>>> >>>>>> Thanks, >>>>>> Han >>>>> >>>>> Hi Han, Numan, >>>>> >>>>> I might have misused "inconsistency" in this context. What I meant was >>>>> more on the note of "discrepancies between NB and SB databases". >>>>> >>>>> This is a very simple reproducer for the port_binding tunnel_key >>> issue, >>>>> no clustering of NB/SB dbs involved: >>>>> >>>>> # Create two logical switches with one port each. >>>>> $ ovn-nbctl ls-add ls1 >>>>> $ ovn-nbctl lsp-add ls1 p1 >>>>> $ ovn-nbctl ls-add ls2 >>>>> $ ovn-nbctl lsp-add ls2 p2 >>>>> $ ovn-nbctl --wait=sb sync >>>>> >>>>> # At this point PB for p1 has tunnel_key=1 >>>>> # At this point PB for p2 has tunnel_key=2 >>>>> >>>>> # Simulate the SB db going away (could be network >>>>> # issues or crash or some other event). >>>>> $ ovn-ctl stop_sb_ovsdb >>>>> >>>>> # CMS decides to move p2 from ls2 to ls1 and removes >>>>> # ls2 completely. >>>>> $ ovn-nbctl ls-del ls2 >>>>> $ ovn-nbctl lsp-add ls1 p2 >>>>> >>>>> # Simulate SB DB coming back online. >>>>> $ ovn-ctl start_sb_ovsdb >>>>> >>>>> At this point ovn-northd will try to set the datapath field in PB2 to >>>>> point to datapath_binding corresponding to ls1 but will *not* change >>>>> tunnel_key. >>>>> >>>>> We get: >>>>> 2020-04-29T20:52:41.327Z|00016|ovsdb_idl|WARN|transaction error: >>>>> {"details":"Transaction causes multiple rows in \"Port_Binding\" table >>>>> to have identical values (1b1c4b39-c045-448d-a532-8edbe5544e13 and 1) >>>>> for index on columns \"datapath\" and \"tunnel_key\". First row, with >>>>> UUID e20219fa-ef67-49a2-81cd-739fa80d2bd4, existed in the database >>>>> before this transaction and was not modified by the transaction. >>> Second >>>>> row, with UUID 50b0e240-8a4d-4e98-8e2f-97c94811d1b1, had the following >>>>> index values before the transaction: >>>>> a9b5959f-2f48-44e7-b6bb-f7148c28e4b5 and 1.","error":"constraint >>> violation"} >>>>> >>>>> And ovn-northd keeps retrying the same transaction at every iteration >>>>> from this point on and fails continuously. >>>>> >>>>> For the stale datapath issue (patch #1 in the series) a similar >>>>> reproducer is: >>>>> >>>>> # Create a logical router with on router port. >>>>> $ ovn-nbctl lr-add lr >>>>> $ ovn-nbctl lrp-add lr p 00:00:00:00:00:01 1.1.1.1/24 >>>>> >>>>> # Simulate that a mac binding was created for the router >>>>> # port. >>>>> $ dp=$(ovn-sbctl --bare --columns _uuid list datapath .) >>>>> $ ovn-sbctl create mac_binding logical_port="p" ip="1.1.1.2" >>> datapath="$dp" >>>>> $ ovn-nbctl --wait=sb sync >>>>> >>>>> # Simulate the SB db going away (could be network >>>>> # issues or crash or some other event). >>>>> $ ovn-ctl stop_sb_ovsdb >>>>> >>>>> # CMS decides to delete lr. >>>>> $ ovn-nbctl lr-del lr >>>>> >>>>> # CMS decides to readd lr and router port. >>>>> $ ovn-nbctl lr-add lr >>>>> $ ovn-nbctl lrp-add lr p 00:00:00:00:00:01 1.1.1.1/24 >>>>> >>>>> # Simulate SB DB coming back online. >>>>> $ ovn-ctl start_sb_ovsdb >>>>> >>>>> At this point ovn-northd will try to clear the old datapath record >>> from >>>>> SB DB *without* destroying the mac binding record. >>>>> >>>>> We get: >>>>> 2020-04-29T21:41:42.145Z|00013|ovsdb_idl|WARN|transaction error: >>>>> {"details":"cannot delete Datapath_Binding row >>>>> de8d19d6-d67b-499b-8825-12d34ec60946 because of 1 remaining >>>>> reference(s)","error":"referential integrity violation"} >>>>> >>>>> I think both situations above should be addressed by ovn-northd and >>>>> stale datapath/mac_binding/port_binding/etc records should be purged. >>> I >>>>> guess there might be other scenarios that would trigger constraint >>>>> violations too but this is what I found so far. >>>>> >>>>> If you agree, I can send a v2 and add tests for the two simplified >>>>> scenarios I mentioned above. >>>>> >>>>> What do you think? >>> >> >> Thanks Dumitru. for the explanation. It would be great to add these tests >> in v2. >> >> Thanks >> Numan >> >> >>>>> >>>>> Thanks, >>>>> Dumitru >>>>> >>>> >>>> Thanks Dumitru for explaining. Now I understand the problem. So it has >>> nothing to do with OVSDB consistency itself, but just northd'd logic. I >>> don't even need to stop SB to reproduce. Here is how I reproduced it: >>>> $ ovn-nbctl ls-add ls1 >>>> $ ovn-nbctl ls-add ls2 >>>> $ ovn-nbctl lsp-add ls1 lsp1 >>>> $ ovn-nbctl lsp-add ls2 lsp2 >>>> $ ovn-nbctl lsp-del ls2 -- lsp-add ls1 lsp2 >>> >>> Sorry for the typo. The last command was: >>> $ ovn-nbctl lsp-del lsp2 -- lsp-add ls1 lsp2 >>> >> > I applied these 2 patches locally and I ran the below commands, which is > the same as the above > commands shared by Han. > > $ovn-nbctl ls-add ls1 > $ovn-nbctl ls-add ls2 > $ovn-nbctl lsp-add ls1 lsp1 > $ovn-nbctl lsp-add ls2 lsp2 > $ovs-vsctl add-port br-int p1 -- set Interface p1 external_ids:iface-id=lsp2 > $ovn-sbctl list port_binding > > $ovn-sbctl list port_binding > _uuid : bbf2f7e4-b61b-4ce8-adb6-4d17e410b87b > chassis : ff506354-ac7b-4463-b42d-d89bddf319c7 > datapath : ef316369-0f2c-4246-adbd-8c187bd95e41 > ... > ... > tunnel_key : 1 > type : "" > virtual_parent : [] > > _uuid : 7cca89fa-55f9-4326-8188-6678838467bb > chassis : [] > datapath : 21263028-a511-457a-824b-39a1219084c8 > ... > logical_port : lsp1 > ... > tunnel_key : 1 > type : "" > virtual_parent : [] > > $ovn-nbctl lsp-del lsp2 -- lsp-add ls1 lsp2 > > $ovn-sbctl list port_binding > _uuid : bbf2f7e4-b61b-4ce8-adb6-4d17e410b87b > chassis : ff506354-ac7b-4463-b42d-d89bddf319c7 > datapath : 21263028-a511-457a-824b-39a1219084c8 > ... > logical_port : lsp2 > ... > tunnel_key : 1 > type : "" > virtual_parent : [] > > _uuid : 7cca89fa-55f9-4326-8188-6678838467bb > chassis : [] > datapath : 21263028-a511-457a-824b-39a1219084c8 > ... > logical_port : lsp1 > ... > tunnel_key : 2 > type : "" > virtual_parent : [] > > > I notice that the same port_binding record for lsp2 is being reused. > Is that intentional ?
This happens because the order in which ovn_port entries will be processed: https://github.com/ovn-org/ovn/blob/master/northd/ovn-northd.c#L3453 The "both" list is populated in join_logical_ports() and depends on the order of Logical_Switch/Router_Port records in od->nbs->ports/od->nbr->ports arrays which is not under ovn-northd's control. https://github.com/ovn-org/ovn/blob/master/northd/ovn-northd.c#L2022 https://github.com/ovn-org/ovn/blob/master/northd/ovn-northd.c#L2103 > > Ideally the old port binding record lsp2 should get deleted and > new one should get created. So even if we delete the old port binding and recreate it we'd still get a conflict in some cases because lsp2 would be processed before lsp1. > > I found another issue with the below commands (tested in sandbox env) > > $ovn-nbctl ls-add ls1 > $ovn-nbctl ls-add ls2 > $ovn-nbctl lsp-add ls1 lsp1 > $ovn-nbctl lsp-add ls2 lsp2 > $ovn-nbctl lsp-set-type lsp2 external > $ovn-nbctl ha-chassis-group-add chg1 > $ovn-nbctl ha-chassis-group-add-chassis chg1 chassis-1 30 > $ovn-nbctl set logical_switch_port lsp2 ha_chassis_group=<chg1_uuid> > $ovn-nbctl lsp-del lsp2 -- lsp-add ls1 lsp2 -> This fails with the below > logs in ovn-northd > > ******* > 2020-04-30T09:59:48.319Z|00007|ovsdb_idl|WARN|transaction error: > {"details":"cannot delete HA_Chassis_Group row > 6e0c88d7-20f6-473a-bd0a-9eea60b639e6 because of 1 remaining > reference(s)","error":"referential integrity violation"} > ******* I'll look into this. Looks like patch #2 of the series should take care of HA_Chassis_Group too. > > I think it's better if the stale port binding entry is deleted instead of > reusing it. What do you think ? As mentioned above, this wouldn't help too much and it would actually create larger transactions so it seems inefficient. Thanks, Dumitru > > Thanks > Numan > > > > >>>> >>>> 2020-04-29T23:46:17.675Z|00007|ovsdb_idl|WARN|transaction error: >>> {"details":"Transaction causes multiple rows in \"Port_Binding\" table to >>> have identical values (be595a3b-3904-4229-9ba2-884b27a86b75 and 1) for >>> index on columns \"datapath\" and \"tunnel_key\". First row, with UUID >>> d4cc6ec5-4817-47c9-aa83-9985d3b7b452, existed in the database before this >>> transaction and was not modified by the transaction. Second row, with >>> UUID >>> b874ab93-d97a-4583-8ac3-c353a40b180d, had the following index values >>> before >>> the transaction: 6940ad91-83c5-4fe9-bab5-4fbec6714b0d and >>> 1.","error":"constraint violation"} >>>> >>>> I will take a closer look at the fix. >>>> >>>> Thanks, >>>> Han >>> _______________________________________________ >>> dev mailing list >>> d...@openvswitch.org >>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >>> >>> > _______________________________________________ > dev mailing list > d...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev